net/sched: cls_flower: validate ct_state for invalid and reply flags

Add invalid and reply flags validate in the fl_validate_ct_state.
This makes the checking complete if compared to ovs'
validate_ct_state().

Signed-off-by: wenxu <wenxu@ucloud.cn>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Link: https://lore.kernel.org/r/1614064315-364-1-git-send-email-wenxu@ucloud.cn


Signed-off-by: Jakub Kicinski <kuba@kernel.org>